1. Field of the Invention
The present invention relates to a novel biorestorative material which is a rubber elastic material, wherein a Knoop hardness can be 10 or more after polymerization.
The biorestorative material of the present invention is a material for restoring the living body, and is specifically used as dental prosthetic materials (e.g. artificial tooth, connector tooth, veneer crown, interim prosthesis, denture base material, etc.), contact lens and nail prosthetic materials. The biorestorative material can also be used as toy materials, general industrial materials, etc.
2. Description of the Prior Art
&lt;Artificial tooth&gt;
An artificial tooth is used in anterior tooth, molar, connector tooth, etc., and is molded by charging a polymerizable compound in a mold under a pressure, and polymerizing under the molding conditions wherein a suitable temperature and time are selected. As the material, a mixed system of polymethyl methacrylate (hereinafter abbreviated to "PMMA") and methyl methacrylate (hereinafter abbreviated to "MMA") or a composite material composed of a high-viscosity polyfunctional methacrylate represented by 7,7,9-trimethyl-4,13-dioxo-3,14-dioxo-5,12-diaza-hexadecane-1,16-diol-dime thacrylate (hereinafter abbreviated to "UDMA") and an inorganic/organic filler has hitherto been used. The artificial tooth is polymerized in the mold, and designed so that the Knoop hardness is from about 11 to 50. It occupies an important position in the dental treatment to repair a missing tooth due to coming out of a natural tooth, and abrasion, coming out, breakage, etc. of a ready-made artificial tooth after production of a denture according to a normal dental method. In general, it is a normal method to conduct morphological correction extraorally using a ready-made resin tooth. Taking the burden and adaptability of patients into consideration, a more precise one can be produced in a shorter time when the morphological correction is conducted in the state where the denture is mounted. However, since a ready-made tooth is hard, it is difficult to deform the ready-made tooth by applying a physical force intraorally or on a model.
&lt;Dental crown restorative material&gt;
There are resin jacket crown, resin veneer crown, etc. having the color tone of a dental crown used when the aesthetic property of the missing dental crown is recovered with a restored piece. As the material, a rigid resin as a mixture of a polyfunctional monomer and an inorganic filler is generally used. On the other hand, an interim prosthesis is a restored piece used temporarily for the purpose of supplying maintenance of occlusion, improvement, pronunciation, masticatory efficiency, etc. for a fixed period until a final prosthetic treatment is conducted. For example, for the purpose of performing protection of the tooth quality or marginal gingiva of the abutment tooth, prevention of secondary caries, prevention of migration of adjacent teeth, recovery of the aesthetic property, etc., a ready-made shell crown, a shell molar and a temporary cover crown produced by using an acrylic cold-polymerizable resin are exclusively used.
&lt;Method for production of artificial tooth&gt;
An integrated artificial tooth is obtained by charging those, prepared by coloring a mixed system of MKA and PMMA, or a composite material in an enamel color, an dentin color or a base color, in a mold, heating under pressure, and performing stepwise molding with changing the mold in order, for example, the enamel portion, dentin portion and then base portion in FIG. 1 and FIG. 4, and the enamel portion and then base portion in FIG. 2 and FIG. 3. As a matter of course, the order of the mold may be reversed. Basically, the artificial tooth is molded under the molding condition that the initial molding is not completed in case of molding each portion, and all molding portions are completely polymerized at the time of the final molding and, furthermore, the chemical reaction between the enamel portion and dentin portion and that between the dentin portion and base portion are performed to bond each other. Since the molded artificial tooth is produced by multi-layer molding, it has burr of the polymerized material. Therefore, a final artificial tooth is completed by passing through a so-called polishing step after crude finishing using a tumbler or hand correction.
Since a conventional artificial tooth and connector tooth are completely polymerized, they are not deformed by a suitable pressure on a wax model denture or a denture base and, therefore, occlusal adjustment can not be performed. In addition, the connector tooth can not be deformed according to steepness of a dental arch and, therefore, considerable time and technique were required to the repair of the denture or production of the denture base.
Since a conventional shell and shell molar are completely polymerized, they are not deformed by a suitable pressure. Therefore, it was difficult to adapt them to the shape of the abutment tooth.
It is difficult to perform morphological correction of a conventional dental crown restorative material for repairing the dental crown surface of the denture or the surface of the natural tooth. Furthermore, it is difficult to reproduce a color tone in a simple and stable manner because a suitable forming and coloring are not provided. Therefore, the quality of repair of the dental crown varied with each dental technician. In addition, it was impossible to bond it directly to the abutment tooth intraorally.
A large-sized thermal/pressure molding machine is required to a conventional method for production of an artificial tooth, and conditions wherein bonding is taken into consideration are required as the molding conditions. Therefore, the range of the molding conditions is narrow and was not easily set.